The invention relates to a tool for injection molding of toothbrush bodies of at least two different plastics components injection-molded in succession.
A tool for injection molding of toothbrush bodies of two different plastics components injection-molded in succession is known from EP 0 678 368 A1. It comprises two mold parts which can be moved relative to each other and together constitute a plurality of groups of parallel mold cavities. One of the mold parts comprises a recess for each group of mold cavities, a mold insert being insertable into the recess. Partial cavities are formed in the mold inserts, these cavities corresponding to the head portion of the toothbrush bodies. The first plastics component is injected into two of in total four groups of mold cavities and the second plastics component is injected into the two remaining groups. After injection of the first plastics component the mold inserts with the molded blanks adhering thereto are lifted from the mold cavities and placed in the mold cavities of the other pair of groups, for injection of the second plastics component.
The mold inserts are arranged on the periphery of a circular turning disc by means of which the mold inserts can be moved between the groups of mold cavities. With that results an arrangement for the mold cavities which generally points radially away from the center of the turning disc. Between the groups of mold cavities remains an area on the mold parts which is not made use of.
The invention makes possible a much more compact arrangement of the groups of mold cavities.
The tool according to the invention has two mold parts which can be moved relative to each other and together constitute at least two groups of parallel mold cavities, and further comprises a rotatable carrier arm mounted for rotation about the axis. One of the mold parts comprises a recess for each group of mold cavities, a mold insert being insertable into the recess. Partial cavities are formed in the mold inserts, which partial cavities each correspond to a head portion of the toothbrush bodies. A first one of the plastics components is injected into a first one of the groups of mold cavities and a second one of the plastics components is injected into a second one of the groups of mold cavities. The mold cavities of the first and second groups are arranged on opposite sides of the rotatable carrier arm, the mold inserts being attached to the carrier arm. The mold cavities are arranged in each group parallel to each other and so as to have an identical orientation. The mold cavities of the first group are arranged so as to lie opposite to the mold cavities of the second group and, with respect to the axis of the carrier arm so as to be point-symmetric to the mold cavities of the second group.
The invention makes it possible to arrange many grouped mold cavities in a space-saving way and close to the center, so that the mold part in which the cavities are formed only has to have a relatively small radial extent. On the whole, there results a reduction in mass and a favorable mass distribution, close to the center, of the mold part. Arranging the groups of mold cavities close to the center allows also a simpler configuration of the heating conduit system. Opening the tool, in particular the lifting of the carrier arm with the mold inserts attached thereto, is facilitated by the compact arrangement, according to the invention, of the groups of mold cavities, because no excessive leverages occur due to the inserts being close to the center.